Quick-setting bituminous emulsion compositions

ABSTRACT

Quick setting, anionic bitumen emulsion compositions, suitable for road paving, recreational surfaces, etc., are formulated by emulsifying the bitumen in water with an ammonium or alkali metal salt of a hydrocarbon-substituted sulfuric, sulfonic, phosphoric or phosphonic acid emulsifier, mixing the emulsion with a fine aggregate and, prior to spreading the aggregate emulsion mixture, introducing an alkaline earth metal set initiator. The resulting composition rapidly breaks to a hard cohesive structure, so as to permit early use by traffic.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No. 16,653,filed Mar. 1, 1979, now abandoned, which is a Divisional of U.S.application Ser. No. 255,604, filed May 22, 1972, which has issued asU.S. Pat. No. 4,193,816, which is a continuation-in-part of U.S.application Ser. No. 672,746, filed Oct. 4, 1967, now abandoned, U.S.application Ser. No. 757,137, filed Sept. 3, 1968, now abandoned, andU.S. application Ser. No. 68,502, filed Aug. 31, 1970, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The ever-increasing traffic and heavy wear to which pavements areexposed aggravates the need for a rapid and efficient means forrepairing pavements to a long wearing surface. Heretofore, slurry sealshave been widely used to repair pavements, but have been deficient inrequiring relatively long times before they hardened to a usefulsurface. The slurry seals set by evaporation. Therefore, the time couldgreatly vary depending on the temperature and humidity, as well as otherenvironmental factors.

In addition, the slurry seals were particularly suceptible to rain. Ifthey has not hardened to a cohesive surface, a rainstorm could rapidlywash away or seriously damage the slurry seal pavement. Because of thedeficiences of prior slurry seals, they have not found the wide usewhich their convenience of application would otherwise suggest.

2. Description of the Prior Art

U.S. Pat. No. 3,513,005 describes an anionic slurry seal employing anorganic sulfonate surface active agent having an ether linkage. U.S.Pat. Nos. 3,206,174 and Re. 26,204 describe an apparatus and methods forapplying slurry seal mixtures. Other patents of interest include U.S.Pat. Nos. 3,206,319; 2,488,252; 2,773,777; and 3,364,046.

SUMMARY

Anionic slurry seal compositions are provided by combining with asuitable aggregate a bitumen in water emulsion, emulsified with anammonium or alkali metal salt of a hydrocarbon sulfonic, sulfuric,phosphonic or phosphoric acid. Prior to laying of the slurry seal, asmall but sufficient amount of a set initiator is added and the slurryseal is spread. The slurry seal composition rapidly sets to a strongcohesive structure, so as to support traffic within a short time.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Slurry seal pavements are provided by combining an anionic bitumenemulsion with a mineral or other aggregate in a solids ratio ofaggregate to bitumen of greater than 1:1. The aggregate and bitumenemulsion are mixed. Prior to spreading of the mixture, at least about0.01 weight percent (based on aggregate) of cement or calcium hydroxideis added as a set initiator, the composition totally mixed and thenspread within not more than five minutes, more usually not more than twominutes of the addition of the set initiator. Upon spreading, thepavement rapidly sets to a hard cohesive surface which is usable withina short time, although one or two days may be necessary before thepavement reaches its ultimate strength.

By rapidly setting it is intended to indicate an aqueous emulsion whichwill coagulate more than 2 percent when tested in accordance with methodASTM D-244. This method involves mixing 100 ml. of the bituminousemulsion to be tested with 50 g. of Portland cement for one (1) minutefollowed by passing the mixture through a No. 14 sieve. The percentcoagulation is determined by the amount retained on the sieve.

In preparing the slurry seals, the normal slurry seal equipment may beused as exemplified in U.S. Pat. No. Re. 26,204. Means are provided formixing the bitumen emulsion and aggregate so as to provide a fairlyhomogeneous mixture. The mixing normally requires from about 0.5 to 5minutes, more usually from about 1 to 2 minutes. The set initiator maybe introduced at any time prior to the spreading of the slurry seal.Preferably, it is added to the aggregate during the initial wetting ofthe aggregate and prior to the addition of the bitumen emulsion. The setinitiator and aggregate are mixed in order to have the set initiatoruniformly distributed throughout the aggregate, followed by addition ofthe bitumen emulsion with continued mixing.

Depending upon the ultimate use of the subject composition, a variety ofaggregates may be employed. Suitable materials include rubber buffings,cut fibers, such as those of bagasse, hemp, organic polymeric fibers,made from polypropylene, polyesters, polyamides, etc.; inorganicmaterials, such as glass fibers, asbestos, etc.; and mineral aggregates,such as gravel, crushed lava, crushed granite, crushed limestone, sand,etc.

The particle size of the aggregate will vary depending upon theparticular use. The particles may range from 1 micron or less to 1 inchor greater. Mixtures containing a large variation of particle sizes aresuitable in particular uses. However, when mineral aggregates are usedin the slurry seals, the particle size would be that within the rangesnormally specified for slurry seals. See the Asphalt Handbook, RevisedEdition, the Asphalt Institute, College Park, Md., September 1960, pages60 and 216-218. Normally, the aggegates are of a particle size in therange of from about 4 to passing 200 mesh, U.S. Standard sieve. Usually,the aggregate will be siliceous or calcareous, illustrated by fine sand,crusher dust, crushed granite, etc.

The bitumen emulsion will be present in from about 3 to 150 parts, moreusually from about 5 to 100 parts, and preferably from about 10 to 30parts based on 100 parts of aggregate. In slurry seals, the emulsionwill normally be present in from about 15 to 25 parts per 100 parts ofaggregate. The emulsion will normally have from about 50 to 70 weightpercent, more usually from about 55 to 65 weight percent of bitumen. Anyof the paving-type asphalts available in commerce will lend itself as asuitable bitumen. In slurry seals, preferred paving bitumens usuallyhave a penetration at 77° F. of from about 40 to 110. The emulsifierwill be present in from about 0.1 to 5, more usually about 0.1 weightpercent to 3 weight percent of the emulsion, and preferably from about0.4 to about 2 weight percent of the emulsion. Other additives may alsobe present, their amounts varying from about 0.05 to 3 weight percent.The remainder of the emulsion will be water, varying usually from about25 to 49.9 weight percent.

Included among the other additives which may be present are bentonite,which can be present in from about 0.1 to 1 weight percent and an alkalimetal salt of phenol sulfonic acid, e.g., sodium phenol sulfonate, whichif present will be in amounts from about 0.1 to about 0.3 weightpercent.

The emulsifiers which find use in this invention have the followingformula:

    R--(O).sub.m --Y(O).sub.n (OH).sub.p

wherein R is a hydrocarbon (i.e., contains only carbon and hydrogen)group of from 8 to 22 carbon atoms, more usually from 12 to 20 carbonatoms and normally having an average number of carbon atoms in the rangeof about 14 to 18 and may be aliphatic, alicyclic, aromatic orcombinations thereof, e.g., alkaryl or aralkyl.

The aliphatic substituent will normally be alkyl or alkenyl. That is,usually there will be only from about 0 to 1 site of olefinicunsaturation. While acetylenic unsaturation may be present, suchcompositions are generally not commercially available and to that extentare not preferred. Where the hydrocarbon group has an aromatic ring, itis preferred that it be alkaryl and particularly preferred that it bealkyl benzene. The alkyl groups bonded to the benzene ring will normallybe of from 8 to 18 carbon atoms, more usually of from 10 to 16 carbonatoms.

Y will be sulfur or phosphorus, preferably sulfur. The O's stand fortheir normal meaning--oxygen.

m will be 0 or 1, n will be 1 when Y is phosphorus and 2 when Y issulfur and p will be 2 when Y is phosphorus and 1 when Y is sulfur. n+pequals 3.

The emulsifiers, therefore, are sulfates, sulfonates, phosphates andphosphonates. They may be used individually or in combination. Thepreferred emulsifiers are sulfonates which may have anywhere from 0 to25 mol percent sulfate. In addition, small amounts of hydroxy alkylsulfonates or phosphonates may be present, depending upon the method ofpreparation. Usually, these will not exceed 10 mol percent.

The compositions where Y is sulfur will have the following formula:##STR1## wherein R¹ is hydrocarbon of from 8 to 22 carbon atoms,preferably of from 12 to 20 carbon atoms having an average number ofcarbon atoms in the range of 14 to 18. The preferred R¹ is aliphatic offrom 10 to 20 carbon atoms, having an average of from 14 to 18 carbonatoms. m may be 0 to 1 and preferably 0.

Particularly preferred are sulfonates derived from olefins, eitherobtained from the cracking of wax (see French Pat. No. 1,419,652 grantedOct. 25, 1965 or a bulletin of Chevron Chemical Company, OroniteDivision, entitled Preparation of C₁₅ -C₁₆ Alpha Olefin Sulfonate (AOS),published in 1966) or polymerization of ethylene. These compositions areprepared by reaction with sulfur trioxide and cracked wax olefins orpolyethylene, followed by neutralization with caustic or potassiumhydroxide.

The emulsifiers having Y as phosphorus will have the following formula:##STR2## wherein R² is hydrocarbon of from 8 to 22 carbon atoms,preferably hydrocarbon from 12 to 20 carbon atoms and particularlypreferred alkyl, alkenyl or alkylphenyl; m is 0 or 1.

The aliphatic groups may be straight or branched chain but arepreferably straight chain. The heteroatom, i.e., oxygen, sulfur orphosphorus may be bonded to a terminal or internal carbon atom, but ispreferably bonded to a terminal carbon atom.

The above acids will be present as their alkali metal salts or as theirammonium salts. By ammonium is intended ammonia and lower alkylsubstituted amines, the alkyl groups being of from 1 to 3 carbon atoms.The alkali metals are lithium, sodum or potassium, preferably sodium.

The pH of the emulsion will be greater than 7 and usually not greaterthan 12, more usually in the range of about 8 to 12. The emulsions areprepared in the normal manner, for example, using a colloid mill.

The set initiator will be Portland cement or hydrated lime or mixturesthereof. The amount of the set initiator will usually range from about0.1 to 5 weight percent based on aggregate, although amounts as low as0.02 weight percent can be used. Usually, the amount of set initiatorwill range from about 0.1 to 3 weight percent, more usually from about0.25 to 2 weight percent. It is found that dehydrated lime is a moreeffective initiator than the cement and, therefore, the hydrated limewill be used in amounts in the lower portion of the range.

The amount of set initiator will be controlled to some degree by theamount of emulsifier present. There will be at least 0.9 equivalent ofcalcium per equivalent of emulsifier, more usually at least 1 equivalentof calcium per equivalent of emulsifier. Generally, the amount of setinitiator will not exceed about 5 equivalents per equivalent ofemulsifier, more usually not exceeding about 3 equivalents perequivalent of emulsifier.

Preferably, during mixing of the aggregate with the set initiator asmall amount of water will be added to wet the aggregate. Usually thiswill not exceed 25 parts per 100 parts of aggregate, and will usually benot less than about 5 parts. Generally, the amount of water will be from5 to 20 parts and usually from 5 to 12 parts by weight per 100 parts ofaggregate.

Once the entire mixture has been combined, the mixture is then rapidlyspread onto the surface to be covered. By virtue of the set initiator,rapid setting occurs and the slurry seal surface becomes rain resistantin as short a time as 15 minutes, forming a black cohesive pad. Withinfrom about 15 minutes to about 1 hour, the slurry seal has acquiredsufficient tensile strength so as to be opened for light vehiculartraffice (automobile).

The following examples are offered by way of illustration and not by wayof limitation.

In a representative series of tests illustrating the operation of theinvention, about 60 percent by weight of a typical paving asphalt (50-60Pen. at 77° F.) was emulsified in water, using for its emulsification0.5 percent by weight of different alpha-olefin sulfonic acids, 0.2percent by weight of phenol sulfonic acid and 0.06 percent by weight ofsodium hydroxide.

In each test, 500 gram samples of two different (silica and limestone)aggregate types and different gradations were employed. The setinitiator added was Portland cement. The amount of cement used (0.5weight percent) was in the preferred range of from about 0.25 to about 2weight percent by weight. Each aggregate sample was then combined withthe emulsion whose weight equaled 25 percent by weight, based on the dryaggregate, and with from about 6 to about 12 percent by weight of water,also based on the weight of the aggregate, the quantity of waterdepending on whether a coarser or a finer aggregate was employed toprepare the slurry. The slurry was poured to fill a round tin can lid,15.5 centimeters in diameter and 2 centimeters deep. The rapidity ofdevelopment of tensile strength in the resulting slurry seal pad wasdetermined by touching the pad's surface with a spatula.

The limestone aggregate was obtained from Rockaway Quarry, Pacifica,Calif. It had a gradation indicated in Table I.

                  TABLE I                                                         ______________________________________                                        U.S. Sieve   Grams Retained                                                                              Weight %                                           Size         from 200 g. Sample                                                                          Retained                                           ______________________________________                                         4           0.0           0                                                   8           0.0           0                                                  16           61.7          30.8                                               30           48.0          24.0                                               50           30.0          15.0                                               100          19.0          9.5                                                200          9.6           4.8                                                thru 200     31.5          15.7                                                            199.8         99.8                                                            Loss: 0.2 gram                                                   ______________________________________                                         Sand equivalent = 81                                                     

Granite dust was obtained from the Logan Quarry, Watsonville, Calif. Ithad a gradiation as indicated in Table II.

                  TABLE II                                                        ______________________________________                                        U.S. Sieve   Grams Retained                                                                              Weight %                                           Size         from 200 g. Sample                                                                          Retained                                           ______________________________________                                         4           0.7           0.35                                                8           7.5           3.75                                               16           33.3          16.6                                               30           35.7          17.8                                               50           32.0          16.0                                               100          29.5          14.7                                               200          21.2          10.6                                               thru 200     39.0          19.5                                                            198.9         99.30                                                           Loss: 1.1 grams                                                  ______________________________________                                         Sand equivalent = 61                                                     

EXAMPLE 1

63 parts by weight of asphalt was emulsified in water using 0.5 part ofC₁₁ -C₁₄ alpha-olefin sulfonic acid, 0.2 percent by weight of phenolsulfonic acid, and 0.06 percent by weight of sodium hydroxide asdescribed hereinabove. On mixing with the aggregate, it was noted thatthe mixing "pot life" ranged from 1 to 2 minutes. When laid on thesubstrate, the emulsion rapidly coalesced within 4 to 8 minutes, and theslurry seal set completely as a cohesive tough black surface in about 1hour.

EXAMPLE 2

Again, 63 parts by weight of asphalt was emulsified as in the precedingtest, but this time using 0.5 part of a C₁₅ -C₁₈ alpha-sulfonic acid(average molecular weight 343). Again a satisfactory "pot life" wasobserved during the mixing with the aggregate. The slurry was completelyset in about 1 hour.

EXAMPLE 3

In this case, 0.5 part of a C₁₅ -C₂₀ alpha-olefin sulfonic acid wasused, other amounts being as in the two preceding tests. The mixing "potlife" was good, in the order of 2 to 4 minutes. Coalescence of theemulsion and setting of the slurry seal occurred somewhat slower in thiscase; hosever, the set was completed to satisfaction in about 1 hour.

EXAMPLE 4

In this test, the alpha-olefin sulfonic acid, used for theemulsification of asphalt as described in the preceding tests, was anequimolar mixture of C₁₁ -C₁₄ and C₁₅ -C₂₀ alpha-olefin sulfonic acid.The mixing "pot life" and the setting times were essentially the same asthose observed in Test 2.

The next test is offered to show that, although the addition of adhesionaid to the emulsion is sometimes desirable, particularly in the case ofphenol sulfonic acid which may enhance adhesion and facilitatesapplication of the slurry seal, the presence of such aids is optional.Bituminous emulsions formulated according to the invention with the aidof sulfonate emulsifiers, such as alpha-olefin sulfonates, are noted tohave a similarly satisfactory extended "pot life" which permitseffectively mixing them with the aggregates and applying them to thepaved surfaces requiring repair.

EXAMPLE 5

In this test, 63 parts by weight of paving asphalt was emulsified inwater with the aid of 0.8 part of alpha C₁₅ -C₁₈ olefin sulfonic acid,using sodium hydroxide as the emulsifying base. The conditions of thetest were otherwise the same as indicated in Test 1. No adhesion aids ofany kind were present. In mixing with the aggregate, the "pot life"ranged from 1 to 2 minutes. Once applied, the slurry seal set to a good,tough cohesive pad in about 1 hour.

EXAMPLE 6

This test was run for comparison with the results observed in Test 5.The proportions of the components for formulating the slurry seal mixwere the same, except for the addition of 0.3 part of phenol sulfonicacid. Again, the "pot life" was of the order of 1 to 3 minutes. Theworkability of the slurry seal, i.e., ease of pouring out, applying andsmoothing, was somewhat improved compared to Test 5. The surfacing setto a tough black pad in 1 hour.

FIELD TEST

In this particular test of the paving mix, prepared in accordance withthe invention and carried out in actual practice, a portion of worn roadsurface, 68 centimeters wide and 12 meters long, was slurry seal-treatedusing the following mixture:

25 parts of asphalt emulsion,

100 parts of aggregate,

11 parts of slurrying water, and

0.75 part of Portland cement.

The emulsion was one prepared by emulsifying 65 percent by weight ofmixed California asphalts having an acid number of 1.5 with 0.5 percentby weight of alpha-olefin sulfonic acid, 0.2 percent by weight of phenolsulfonic acid, and 0.06 percent by weight of sodium hydroxide. Themixture of emulsion and aggregate has a "pot life" of about 3 minutes.It was immediately applied by screeds, and the emulsion coalesced in 4to 8 minutes. The seal set completely in about 30 minutes as a blacktough surface which was then opened to vehicular traffic by automobilesand trucks. After ten weeks, no perceptible damage could be observedover the area, which was a part of the driveway to a petroleum refineryproduct bulk station with an average hourly heavily laden truck trafficdensity of 3 to 4 vehicles.

EXAMPLE 7

In a similar manner as in Example 1, 63 parts by weight of asphalt wereemulsified in water using 0.5 part of octylphenol acid phosphate as theemulsifier. A "pot life" of 2 minutes was obtained with a resultingcohesive tough, black surface.

EXAMPLE 8

The procedure of Example 7 was repeated, employing as the emulsifierPhosphonol N, which is a complex alkyl phosphoric acid marketed bySterwin Chemicals, Inc. Again, a 1 minute "pot life" with a resultingtough coating was achieved.

EXAMPLE 9

The procedure of Example 1 was followed, employing as the emulsifier 1.0percent by weight, Duponol ME, which is sodium lauryl sulfate marketedby E. I. du Pont de Nemours and Company. Excellent "pot life" and atough cohesive coating were achieved.

PREPARATION OF RECREATIONAL SURFACES WITH QUICK-SETTING ANIONICEMULSIONS

In a manner similar to the preparation of the slurry seals, a runningtrack base was prepared employing the alpha-olefin sulfonate ofExample 1. The solid particulate matter comprised in relation to thetotal weight of mixture, 28.0 percent of rubber buffings, 28.0 percentsand, and 0.3 percent bentonite clay. 1.15 percent of trisodiumphosphate was added 1.6 percent by weight of a synthetic rubber latexemulsion and 0.5 percent by weight of an organic magnesium salt defoamerwere employed in the mix. 2.4 percent of hydrated lime was used as theset initiator. The resulting composition had a "pot life" of about 2minutes and set into a tough elastic film.

It is evident from the above results that the compositions of thisinvention provide a satisfactory "pot life" for homogeneous mixing ofthe compositions. Furthermore, once the compositions are spread, theyrapidly set to a hard cohesive surface with good adhesion to theaggregate. Thus, the slurry seal covered surfaces may be used shortlyafter the laying of the slurry seal so as to prevent a minimum ofinterruption in use of the facility.

We claim:
 1. A surfacing composition which rapidly sets to a toughcohesive surface with early development of tensile strength and rainresistance and is prepared by intimately mixing a solid particulatematter, a bituminous emulsion having a pH greater than about 7, and aset initiator in the following proportions: which comprises 100 parts byweight of a solid particulate matter, 0.1 to less than 5 parts by weightof a set initiator which is Portland cement, hydrated lime, or mixturesthereof; and from about 3 to 150 parts of a bituminous emulsioncomprising from about 50 to 70 weight percent of a bituminous binder andfrom about 0.1 to about 3 weight percent of the anionic ammonium oralkali metal emulsifying salt of a compound selected from the groupconsisting of a hydrocarbyl phosphoric acid, a hydrocarbyl phosphonicacid and mixtures thereof, wherein the hydrocarbyl moiety is from about8 to 22 carbon atoms.
 2. A composition according to claim 1, whereinsaid emulsifying salt has the following formula: ##STR3## wherein R² isalkyl, alkenyl or alkylphenyl of from 8 to 24 carbon atoms and m is 0or
 1. 3. The composition according to claim 2 wherein the ammonium saltis a lower alkyl substituted amine wherein the alkyl groups are from 1to 3 carbon atoms and the alkali metals are selected from the groupconsisting of lithium, sodium, and potassium.
 4. The compositionaccording to claim 3 wherein the pH of the bituminous emulsion is fromabout pH 7 to about pH
 12. 5. The composition according to claim 2wherein said bituminous emulsion concentration is from about 5 to 100parts.
 6. The composition according to claim 5 wherein the set initiatoris present in an amount of from about 0.1 to about 3 weight percent. 7.The composition according to claim 1 further comprising water in anamount equal to or less than about 25 parts per 100 parts of solidparticulate matter.
 8. The composition according to claim 7 wherein thesolid particulate matter is selected from the group consisting of rubberbuffings, bagasse, hemp, organic polymeric fibers, inorganic aggregates,mineral aggregates, and mixtures thereof.
 9. A process of forming asurfacing composition comprising:mixing a solid particulate matter;introducing a composition to said solid particulate matter whichcomprises about 0.1 to less than 5 parts by weight of a set initiatorwhich is Portland cement, hydrated lime, or mixtures thereof; and about3 to 150 parts of a bituminous emulsion per 100 parts by weight of solidparticulate matter wherein said bituminous emulsion has a pH greaterthan about 7 and comprises 50 to 70 weight percent of a bituminousbinder and from about 0.1 to about 3 weight percent of the anionicammonium or alkali metal emulsifying salt of a compound selected fromthe group consisting of a hydrocarbyl phosphonic acid, a hydrocarbylphosphoric acid, and mixtures thereof; and, mixing said solidparticulate matter and said composition for a sufficient time to form ahomogenous mixture.
 10. The process according to claim 9 wherein saidcomposition and said solid particulate matter are mixed for about 0.5 to5 minutes.
 11. The process according to claim 9 wherein the setinitiator is introduced to and mixed with the solid particulate matterprior to introducing said composition.
 12. The process according toclaim 11 wherein water in an amount less than about 25 parts per 100parts of solid particulate matter is added during the mixing of said setinitiator and said solid particulate matter.
 13. The surfacingcompositions produced according to the process of claims 10 or 12.